Afternoon colonoscopies have higher failure rates than morning colonoscopies

There are several known predictors of an incomplete colonoscopy or difficult colonoscopy. In addition, inadequate bowel preparation has been reported in procedures scheduled later in the day. Operator fatigue, which tends to be higher as the day passes on, may also impact colonoscopy completion rate.

To determine the influence of performing outpatient colonoscopies in the afternoon versus morning on the completion rates of colonoscopy and adequacy of bowel preparation.

Retrospective chart review of all outpatient colonoscopies performed between November 2003 and October 2004 in the Division of Gastroenterology at MetroHealth Medical Center in Cleveland, Ohio. Patient demographics, indications for procedure, and colonoscopic findings were reviewed. Patients received polyethylene glycol electrolyte-based bowel preparation in the evening prior to the day of the scheduled colonoscopy.

A total of 2,087 colonoscopies was performed, of which 1,084 were in the morning and 999 were in the afternoon. Patients in the morning and afternoon were similar in regards to the known risk factors predictive of an incomplete colonoscopy. The incompletion rate was significantly higher in the afternoon compared to the morning (6.5% vs 4.1%, P= 0.013, OR for incompletion was 1.64, CI 1.11-2.44). Inadequate bowel preparation was found in 167 out of 1,084 (15.4%) colonoscopies in the morning and 197 out of 999 (19.7%) colonoscopies in the afternoon (P= 0.011). Even after excluding incomplete colonoscopies due to poor bowel preparation precluding examination, the incompletion rate was still higher in the afternoon (5% vs 3.2%, P= 0.043, OR 1.60, CI 1.03-2.51).

Scheduling of colonoscopies in the afternoon compared to the morning may be an independent predictor of an incomplete colonoscopy and inadequate bowel preparation. According to our study findings, scheduling of all outpatient colonoscopies preferentially in the morning would avoid suboptimal procedures in 5% of patients and the need for unnecessary repeat colonoscopy or an alternative imaging study in 2.4% of patients.